1. Field of the Invention
This invention relates to devices for applying a tubular member over a container and, more specifically, to flexible adjustable wedges for opening flattened heat shrinkable tubing.
2. Prior Art
In many industries, particularly the pharmaceutical industry, it is desirable to provide for the cap sealing of product containers for reasons of safety, tamper-proofing, sanitation, etc. Several known apparatus exist for effecting such desired cap sealing. One particularly advantageous apparatus is described in U.S. Pat. No. 4,562,684 to Hans Dreher, which disclosure is incorporated herein by reference.
Typically, such apparatus include a supply of flattened tubular heat shrinkable members, a pickup mechanism, means for opening the tubular members, means for delivering the opened tubular members to an application station, means for applying the opened tubular members to containers as they are conveyed past the application station and means for heating the tubular members so that they shrink around and conform to the shape of the containers thus sealing the containers.
The tubular material is generally supplied to the apparatus by loading pre-cut individual members into a hopper or by employing a continuous web of flattened tubular material that is cut into individual members. In apparatus in accordance with U.S. Pat. No. 4,562,684 the heat shrinkable film material is supplied as a flattened tube wound onto a supply roll. In processing this film material, an opening means is employed to relieve the material from its compressed, flattened state. This permits the preopened film material to be more readily machine-opened after being cut to length and makes it easier to apply it to the container for shrinking.
Prior art opening means for performing this preopening operation include a solid triangular wedge of fixed dimension, sized to operate on a given roll of film and solid triangular wedges having flexible members fixed in the corners of the wedge to allow for slight variations in the film dimensions. This capability is necessary because when tubular film manufacturers supply the rolls of material there is an inherent flat width variation. That variation can be exaggerated by some pre-shrinking of the film due to exposure to heat during the shipping and/or storage phase. Consequently, by the time the film is used on tamper evident machinery, the flat width of the film material can be several millimeters off specification and can result in manufacturing problems and excessive down time of the machine. For example, film material which, upon delivery, is off specification and, as a result, too small for the fixed dimension solid triangular wedge will not be able to fit over the wedge and will split the film and stop production.
The solid triangular wedge with corner mounted flexible members does allow for more variation in the flat film width. However, there are times when these variations are too large to be accommodated by the flexural capabilities of the flexible solid wedge. Further, there are many instances when the tamper evident machines must be adapted to another size product which requires film of a different flat width. Such a changeover using prior art wedge designs require the substitution of different wedges for each roll of film having a different flat width.
It is an object of the present invention to provide a flexible adjustable wedge for use with tamper evident machines for applying heat shrinkable tubular film wherein the wedge can accommodate wide variations in flat film width.
It is another object of this invention to provide a flexible adjustable wedge which is flexible to accommodate minor variations in film width without requiring removal of the wedge from the machine.
It is a further object of this invention to provide a flexible adjustable wedge that is simple in construction and can be easily adjustable without excessive down time of the machine.